Primary role of the structural phase transition in the strongly coupled structure and magnetism of La_0.835Sr_0.165MnO₃ single crystal

We report a neutron diffraction investigation of the role of pressure on the strong coupling between the structural and ferromagnetic phase transitions in La0.835Sr0.165MnO3. The results are summarized in the form of a pressure-temperature phase diagram and reveal the dominant character of the structural changes with respect to the magnetic transitions, which results in a broad metastable area around the crossing point of the structural and magnetic phase transitions. The phase diagram contains a number of extremely unusual features including the pressure independence of the Curie temperature in the orthorhombic phase, a reentrance of the rhombohedral phase at low temperatures, and a change of the type of the magnetic phase transition from second order to first order due to the strong coupling between the structural and the magnetic properties of this material.